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One of the CBI Molecules being studied in the University of Massachusetts Amherst Chemistry-Biology Interface Program at UMass Amherst and on display at the Molecular Playground.

The bacterial chemotaxis receptors are transmembrane receptors with a simple signalling pathway which has elements relevant to the general understanding of signal recognition and transduction across membranes, how signals are relayed between molecules in a pathway, and how adaptation to a persistent signal is achieved.

Bacterial chemotaxis receptors are composed of a ligand-binding domain, a transmembrane domain consisting of two helices TM1 and TM2, and a cytoplasmic domain. All known bacterial chemotaxis receptors have a highly conserved cytoplasmic domain, which unites signals from different ligand domains into a single signalling pathway to flagella motors.

''Four-helical-bundle structure of the cytoplasmic domain of a serine chemotaxis receptor., Kim KK, Yokota H, Kim SH, Nature. 1999 Aug 19;400(6746):787-92.''

Cytoplasmic domain of TSR


The structure of the cytoplasmic domain of a serine chemotaxis receptor(TSR) of Escherichia coli is a 200 A-long coiled-coil of two antiparallel helices connected by a 'U-turn'. Two of these domains form a long, supercoiled, four-helical bundle in the cytoplasmic portion of the receptor.